A gas as a fuel for internal combustion engines in marine vessels has become more common because of the environmental reasons. At the same time the equipment for handling and regulating gas fuel is subjected to stringent safety regulations. A gas valve unit is commonly referred to a module located between a gas storage system and an engine, for instance a so called dual-fuel engine in a marine vessels. One gas valve unit is required for each engine, or generally for each gas consumer. It is used mainly to regulate the gas pressure and ensure a safe disconnection of the gas system, if so desired. The gas valve unit comprise an enclosure, gas piping and several additional components, for example filters and valves, inside the enclosure for measuring and regulating gas.
Before using the enclosed gas valve unit, the enclosure, as well as the gas supply piping, has to be pressure tested. The gas valve unit with enclosed design is usually pressure tested at the factory with presence of class surveyor.
The gas valve unit with enclosed design is pressure tested at the factory with presence of a class surveyor.
Contrary to enclosure, an inlet and an outlet gas pipe connected to a gas valve unit has to be tested on the installation place, in a marine vessel. For instance, at the vessel new welding seams are made on the gas lines when adjusting and attaching the gas valve unit's gas inlet and outlet pipe to the gas piping of the vessel. Lifting the gas valve unit to its exact position and connecting it to gas supply piping requires flexibility, for example necessary tolerances has to be taken into account. Final welds are made when unit is at the final installation position.
Due to safety reasons, water is usually used for pressure tests. However, water entering into the enclosure of the gas valve unit will cause problems for measuring components and other possible instruments that are sensitive to water.
An object of the invention is to provide a gas valve unit with a solution for pressure test arrangement of the annular space of the double wall pipes upstream and downstream of the gas valve unit in which the test setup is considerably improved compared to the prior art solutions.